Rainfall is the most important factor in triggering the landslide. To reduce the loss of life and property caused by the landslide disaster

the early warning system against landslides becomes one of the best choices. Based on the principle of elastic wave propagation and the characteristics of deformation and failure of rainfall-induced landslides

this paper proposes to use the elastic wave velocity to detect the changes in soil moisture content and displacement on slope surface. The bender elements and ceramic disk

incorporated in a triaxial apparatus

are used to measure the S-wave and P-wave velocities in soils subjected to water infiltration. The device allows water to infiltrate into the soil from the pedestal to simulate the process of rainfall infiltration into the soil. The moisture content

deformation and elastic wave velocity are simultaneously measured during the tests. Besides

the rainfall model tests are carried out. Based on the triaxial model tests

this study reveals the process of rainfall-induced landslides

the evolution of elastic wave velocity

and the coupling relationship among the wave velocity

water content and deformation. The results show that the elastic wave velocity decreases slowly with the increase of water content

but decreases sharply with the increase of deformation

indicating the initiation of the instability. We also interpret possible mechanisms of the reduction of elastic wave velocity caused by water content and deformation. This paper provides a new method and reliable basis for an early warning system for rainfall-induced landslides and slope failures.